Previously a wide variety of ways have been used to represent numerical data. The ancient Romans used their letter symbols to write numbers. When we use this method today we call them Roman numerals. History also tells us that in the ninth century A.D. an unknown Hindu devised a method using ten new symbols. He did not use a new symbol for ten as the Romans did but used the one symbol spaced to the left of the nine symbol and replaced the nine symbol with a zero symbol. This was a significant advance. When we use this method today we call the numbers Arabic numerals.
A set of ten new symbols has recently been devised to print our account number on our checks in magnetic ink so the number can readily be read by machine. It is wise to learn to read these symbols because these symbols are also used to write the amount of the check in dollars and cents, just to the right of the account number, again with magnetic ink, so the amount can be read by machine.
Another variation of the ten Arabic symbols is found on packages of items sold in stores. It is an array of parallel lines, some thin and some thick, which can be read by a photoelectric device. These symbols have been referred to as bar codes.
It is the belief of the inventors that there is need for still another variation of the Arabic symbols, which would have an analog connotation, so that one can look at a series of numbers and immediately see trends and other changes of interest to him.
Processes have been devised for the purpose of recording digital information in analog form. U.S. Pat. No. 3,039,101 to Perdue discloses a method for plotting digital data with analog connotation. The patent discloses the plotting of three decades of information. The most significant decade determines the position of the marking on the chart. The decade of next significance determines the size of the symbol thus refining the analog connotation. The decade of least significance determines the size of a symbol in the margin which allows more resolution if needed. The maximum size of the Perdue symbol is ten dots with nine spaces therebetween. A chart size ten times the maximum symbol size is required for a full decade of most significance. U.S. Pat. No. 3,550,148 to Machler uses a symbol having a maximum size of only five dots with four spaces therebetween. Since this symbol size is only half the size of the Perdue symbol the amount of chart required for the decade of next greater significance is only half that required by Perdue. This permits Machler to include positioning from a decade of still greater significance and so record three decades of information without placing any of the information in the margin. U.S. Pat. No. 3,214,764 to Williams discloses a different method for plotting digital data with analog connotation. The disclosure shows five decades while using less chart space than Perdue and Machler, showing three decades. The Williams method uses, in part, the teaching of the ninth century Hindu by making multiple use of a set of symbols. It differs from the Hindu method by using twenty symbols instead of only ten. All of the twenty symbols have the same size, equivalent to 41 dots with 40 spaces therebetween. The reason for twenty symbols rather than ten is to give a smoother curve in each decade.